. The Bell System technical journal . - possible because the scales are linear. Thus nozero readings have to be subtracted from the measurement readings and theneed for a separate zero setting phase-shifter is avoided. The phase-shifter is calibrated by a method of substitution. As dis-cussed previously the phase-indicator indicates balance uniquely in mul-. 11—Phase shifltT scales and projected index. tiples of 360° phase-shift. sub-multiples of 360° can be generatedand used to calibrate the phase-shifter. For example (Fig. 12), to establish an exact 180° phase-shift the standardphase-
. The Bell System technical journal . - possible because the scales are linear. Thus nozero readings have to be subtracted from the measurement readings and theneed for a separate zero setting phase-shifter is avoided. The phase-shifter is calibrated by a method of substitution. As dis-cussed previously the phase-indicator indicates balance uniquely in mul-. 11—Phase shifltT scales and projected index. tiples of 360° phase-shift. sub-multiples of 360° can be generatedand used to calibrate the phase-shifter. For example (Fig. 12), to establish an exact 180° phase-shift the standardphase-shifter is set to an arbitrar}- starting point. With the switches inthe position shown a null is obtained on the indicator by adjusting theauxiliary phase-shifter. The network of nominally 180° phase-shift isinserted and a null obtained on the indicator by adjusting the standardphase-shifter. Now the network is removed and the null reestablished byadjustment of the auxiliary phase-shifter. The 180° network again isinserted and a null obtained by adjustment of the standard phase-shifter,which now has been moved through twice the actual phase-shift of the 236 BELL SYSTEM TECHNICAL JOURNAL nominal 180° network. The amount the standard phase-shifter failed toreturn to the original starting point indicates the residual error of the 180°network. T
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
